1. Field of the Invention
The present invention relates to a battery, and more particularly, to a battery parameter management system and a battery parameter estimation method, which are capable of estimating parameters of elements forming a battery model which considers factors having an effect on inherent characteristics and operation characteristics of a secondary battery such as a lithium ion battery.
2. Description of the Related Art
When a secondary battery such as a lithium ion battery used as a power source of an electric driving motor of a hybrid electric vehicle is excessively discharged, the secondary battery may permanently lose the battery's characteristics. Furthermore, when the secondary battery is excessively charged, explosion or fire may occur. Therefore, attention must be paid to charging and discharging. In order to stably charge and discharge a battery, it is necessary to estimate the current state of the battery, that is, the state-of-charge (SOC) of the battery.
In order to accurately estimate the state of a battery, it is usual to select a battery equivalent model suitable for the battery. Outside the battery, only an open-circuit voltage of the battery and a current flowing in the battery can be measured. The measured voltage and current are used to estimate the parameters of electric elements forming the battery equivalent model.
When the battery equivalent model is set to have an excessively complex structure, it is naturally expected that an equation for estimating parameters of the elements used in the battery equivalent model will be complicated due to the electrical and physical characteristics of the elements and the electrical connection between the elements. When the battery equivalent model has a complex structure, a large number of function blocks to compute the complicated equation are required. Therefore, when the estimation for the parameters of the elements forming the battery equivalent model is implemented in hardware, the hardware may occupy a considerably large area. When the estimation for the parameters of the elements is implemented in software, a high-performance expensive processor is required.
Therefore, when the estimation is implemented in hardware or software, it is not easy to implement the estimation with one integrated circuit in terms of area and cost.